Absorption cooling for aircraft trolleys and compartments

ABSTRACT

Embodiments of the present invention relate generally to improved cooling systems and methods for use on aircraft trolleys and compartments. The systems use absorptive cooling with thermal conductive plates strategically positioned in order to keep trolleys and their contents cooled.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/712,368, filed Oct. 11, 2012, titled “Absorption Cooling Used on Galley's Trolley Compartment,” and U.S. Provisional Application Ser. No. 61/712,370, filed Oct. 11, 2012, titled “Absorption Cooling Used on Trolley Cooling,” the entire contents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to improved cooling systems and methods for use on aircraft trolleys and compartments.

BACKGROUND

Aircraft trolleys are used to chill and maintain the temperature of food and various other items that are to be served on-board an aircraft. The trolleys are generally chilled via an airflow from an air chiller or compressor that is directed over the items in the trolley. In many instances, the trolley has an opening in the back that can be aligned with a cool air blower that causes air to flow into the trolley and around the food and beverage items contained therein. This configuration can make it difficult to move and interchange the trolleys. Improvements to these cooling systems would be beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side cross-sectional view of a trolley cooling system.

FIG. 2 shows a side cross-section view of an alternate trolley cooling system.

FIG. 3 shows a schematic of the trolley cooling systems of FIGS. 1 and 2.

FIG. 4 shows a top plan view of an alternate trolley cooling system.

FIG. 5 shows a schematic of the trolley cooling system of FIG. 4.

DETAILED DESCRIPTION

Absorption cooling uses a heat source to drive the cooling system. For example, an absorption refrigerator is a refrigerator that uses a heat source (such as a solar source, a kerosene-fueled flame, or waste heat from factories) to provide the energy needed to drive the cooling system. In the early part of the twentieth century, the vapor absorption cycle using water-ammonia systems was widely used, but upon development of the vapor compression cycle, it lost much of its use. Absorption cooling technology has not been used for air conditioning or chilling inside aircraft.

The present inventors have determined that if an appropriate heat source could be provided, the use of absorption cooling on-board aircraft or other vehicles could be a viable alternative to the cooling that is provided by air chillers or compressors in order to recycle the heat and to reduce noise from the traditional cooling systems. Replacing an electric air chiller with an absorption cooler can also reduce electricity loads. Embodiments of the present invention thus provide absorption cooling systems for trolleys and other containers in aircraft or other vehicle galleys. In a specific embodiment, the waste heat used to power the cooling system is provided from a fuel cell, which produces heat as one its by-products. Fuel cell technology has been contemplated by the current assignee and its related companies for powering more and more aircraft systems, particularly various galley (and lavatory) systems, because it is a clean and efficient power source. However, the primary way to make fuel cell technology efficient is by using the fuel cell by-products (water, heat, and oxygen depleted air) in addition to the energy created that is created by the fuel cell. One way to use the heat created is by delivering the heat to an absorptive cooling system. It should be understood that the heat may be provided from other aircraft systems, such as waste heat from one or more of the on-board ovens, from the aircraft engines, from the water system, or any other appropriate source.

In one embodiment, there is provided a system 10 for absorptive cooling an aircraft trolley 12 or other compartment for use on board a passenger transport vehicle. As shown in FIG. 1, a thermal conductive plate 14 is positioned on the back 16 of the trolley 12, and another thermal conductive plate 18 is positioned on the back of the galley trolley bay 20 (the space into which the trolley 12 is stored) for thermal connection. A fan 22 may be provided inside the trolley in order to generate air distribution through the trolley and over the items contained therein. This is an example of an “air over trolley.” The thermal plates transfer the cold temperature that is generated by the absorption cooler to the trolley interior. Contact between the plates 14, 18 creates a thermal connection for a cooling exchange between the plates. The thermal plates 14, 18 are mounted in such a way that they fully contact (or can otherwise be adjusted to fully contact) or substantially fully contact the other thermal plate to have maximum heat (cold) transfer. The transfer is conducted via thermal conductivity in the plates.

FIG. 1 also illustrates that a heat source 24 is positioned behind the monument back wall 20 and associated with the absorption cooling system 10. Waste heat from the heat source 24 is used to power the absorption cooling system 10. In a specific embodiment, the heat generated may be a by-product from a fuel cell used to power one or more aircraft systems.

A cooling fluid circuit 26 is also provided behind the back wall of the trolley bay 20. The coolant circuit 26 is associated with the thermal plate 18 of the back wall, as well as with the absorption cooling unit. As waste heat (with a temperature generally between about 50-90 ° C., and in some instances, between 60-80° C.) is transformed by the absorption cooler, the coolant circuit 26 delivers the cooled fluid to the thermal plate 18. Its contact with the thermal plate 14 of the trolley transfers the cold to the trolley 12. Fan 22 helps recirculate cooled air inside the trolley 12. Although the Figures show a single trolley being interfaced with a single galley wall, it should be understood that the coolant circuit 26 may route cooled fluid to any number of galley bay locations such that multiple trolleys may be cooled at a time.

An adjustment system may be provided to ensure contact between the plates 14 and 18. Because the trolley has clearance and is moveable, an adjustment system may assure correct alignment of trolley to allow contact between the plates.

FIG. 2 shows an embodiment with a duct 28 that has a fan 29 for air distribution or recirculation through the trolley 12. Current installations also have ducting that may be connected to the air-chiller, which contains the cooling parts and a fan to recirculate the air through the ducting and the trolley (referred to as an “air through trolley”). It is desirable to use standard trolleys in connection with this disclosure. In this instance, the trolleys are provided with thermal conductivity via plate 14, such that there is no need for electricity for the internal fan 22 as shown in FIG. 1. In this embodiment, there are holes present on the back of the trolley, through will cold air may be forced into and through the trolley. As the trolley is being cooled on the inside by means of the plate 14, the fan can recirculate the air, creating a more steady atmosphere for the food/drinks inside the trolley. This is an example of an “air through trolley.”

The schematic of FIG. 3 shows how waste heat is delivered to an absorption cooler that uses the heat to drive the cooling system. The cooled fluid may take a first path and be delivered to a compartment to be chilled, as necessary. It may also be delivered to the fluid coolant circuit to cool a galley wall thermal plate 18. The coolant circuit 26 may use any appropriate cooling fluid (such as refrigeration fluid, cooled air, cooled water, or any other fluid). In addition, any other form of heat/cold transportation can be used to deliver cooling fluid between the plates. Non-limiting examples include the thermal conductivity described, the use of heating pipes in contact, cooled air generation, and so forth.

As discussed, in one aspect, thermal plate 18 on the monument aligns with a thermal plate 14 that is mounted on the back of the trolley to generate the desired cooling effect. This system uses less power than an air chiller, it uses waste heat and thus improves efficiency, it provides cooling directly in the area where it is needed, and it provides a modular principle that can be used with each trolley inside the trolley bay.

Another embodiment that uses absorptive cooling technology for chilling trolleys is shown in FIGS. 4 and 5. This concept provides an envelope of cooled air around the trolley, rather than using a thermal plate directly positioned on the trolley. As shown in FIG. 4, the trolley cooling system includes thermal cooling plates 30 on the galley stowage area, and they may be included on the top (the view of FIG. 4 shows a top view so the top plate is not shown), back wall 36, as well as on the divider wall panels 38 between trolley storage areas. The cooling fluid from the absorption cooler may be pumped through these plates 30, much like how the cooling fluid circuit cools the monument plate 18 described above. Providing a plate 30 on the divider wall panel 38 allows the sides of two trolley carts 12 to be cooled with a single plate. This adds to efficiency of the system as the heat (cold) transfer happens on both sides. This creates a cooled or refrigerated area into which the trolley can be positioned. A door or other cooled air containment feature may be added to the front of the trolley bay stowage area, but is not necessary as cooled air is generally desirable in the aircraft galley and cabin areas.

The trolleys may include internal fans (as discussed above) to help move and recirculate cooled air through and over the items in the trolley to improve cooling efficiency and to create an even temperature range. External fans 40 may also be mounted to the back of the galley stowage space and are provided in order to circulate air over the trolley(s) to support the natural recirculation of air and to keep the temperature even in the trolley bay.

These embodiments can alleviate the need for a duct pipe that is typically provided at the back of the monument to deliver chiller air from the air chiller to the trolley. Providing even slight space gains can translate to major costs savings for the airline, as a few inches of space saved can mean additional passenger seats that can be added to the aircraft. One of the other benefits of the above-described solutions is that they do not require modifications to current trolley designs or sizes, nor to the current catering processes. They also reduce electricity loads on the aircraft by providing cooled air using waste heat from fuel cells or other sources.

Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the invention and the following claims. 

What is claimed is:
 1. A cooling system for a trolley positioned in a galley bay, the galley bay having one or more stowage areas for trolleys, comprising: (a) a waste heat source; (b) an absorptive cooler; (c) a cooling fluid circuit; and (d) at least one thermal conductive plate positioned on at least one wall of the stowage area of the galley bay, wherein waste heat from the waste heat source is delivered to the absorptive cooler which uses the waste heat to drive the cooler, wherein the cooling fluid circuit delivers cooled fluid to the at least one thermal conductive plate, and wherein the at least one thermal conductive plate delivers cooling to a trolley.
 2. The system of claim 1, wherein a trolley is positioned in the stowage area of the galley bay and wherein the trolley comprises a thermal conductive plate positioned on its back wall to contact the at least one thermal conductive plate on the wall of the stowage area.
 3. The system of claim 1, wherein the stowage area comprises a top wall, a back wall, and a divider wall panel, wherein a thermal conductive plate is positioned on the top wall, the back wall, and the divider wall panel.
 4. The system of claim 1, wherein the cooling system is used on board a passenger transport vehicle.
 5. The system of claim 1, wherein the cooling system is used on board an aircraft.
 6. The system of claim 1, wherein the waste heat source comprises a fuel cell.
 7. A method for cooling a galley trolley stowage area, comprising (a) delivering heat from a heat source to an absorptive cooler; (b) delivering cooled fluid from the absorptive cooler through a cooling fluid circuit to at least one thermal conductive plate positioned on a wall of the galley trolley stowage area.
 8. The method of claim 7, wherein the at least one thermal conductive plate is positioned on a back wall of a galley monument.
 9. The method of claim 8, further comprising positioning a trolley against the back wall of the galley monument, wherein the trolley comprises a thermal conductive plate positioned on its back wall such that it contacts the at least one thermal conductive plate on the back wall of the galley monument.
 10. The method of claim 7, further comprising a plurality of thermal plates positioned on walls of the galley trolley stowage area, such that the thermal plates create a cooling environment for a trolley positioned in the trolley stowage area.
 11. The method of claim 10, wherein the plurality of thermal plates are positioned on a top wall of the galley monument and a divider wall panel of the galley monument. 